The beheading of reporter James Foley by a Islamic State fighter believed to be from the UK is "an utter betrayal of everything the British people stand for", the Foreign Secretary has said.

Writing in the Sunday Times, Philip Hammond said it was horrifying that the perpetrator "could have been brought up in Britain".

He said the Government was investing "significant resources" to tackle "a barbaric ideology", warning that if the IS militants are not stopped in Iraq and Syria "sooner or later they will seek to strike us on British soil".

The UK Government has also appointed Lieutenant General Sir Simon Mayall as security envoy to the Kurdistan region of Iraq to help with efforts to defeat IS.

Foley was killed by a jihadist with an English accent

A Downing Street spokesperson said: "General Mayall will support Kurdish and wider Iraqi efforts to counter ISIL and work with Iraq's leaders as they establish a unity government."

But former shadow home secretary David Davis dismissed suggestions the new laws, dubbed asbos for terrorists, would prevent Britons fighting for Islamic State (IS), also known as ISIS and ISIL.

Instead, he said, the jihadists should be stopped from returning to the UK and be stripped of their citizenship.

Mr Davis said the Government's response to the crisis in Iraq had been "tentative, uncertain, almost limp".

He suggested the men heading overseas to fight were committing treason.

In an article for the Mail on Sunday, Mr Davis wrote: "Asbos for terrorists? It is hard to imagine the ISIS killers quaking in their boots."

He added: "Since these young men are in effect swearing allegiance to a hostile state, they should all forfeit their British citizenship - not just those who are dual nationals."

Mr Davis' call was echoed by Lord Carey, former Archbishop of Canterbury, who also called for Britons fighting for IS in Iraq and Syria to lose their passports.

Lord Carey wrote in the Mail on Sunday: "They should not have access to the privilege of travelling under a British passport... and they certainly should not be able to travel back with the barbaric and bloodthirsty skills they have gained."

Video:Massacre Fears In Iraqi Town

It comes as it was reported that MI5 and MI6 have worked out the identity of Mr Foley's killer, known as "Jihadi John". But the Sunday Times said no details have been disclosed.

The Home Office has insisted it will take the "strongest possible action" against people travelling to fight in Iraq and Syria.

A spokesman said: "The police, security services and Border Force are actively working to identify, detect and disrupt terrorist threats, including from British fighters attempting to return to the UK.

"They use a wide range of powers, including those which allow them to detain and interview individuals at the UK border suspected of being involved in terrorism.

"In addition to full passport checks, individuals travelling into the UK are checked against watchlists to ensure public safety.

"And the UK uses the most advanced technology in Europe to ensure we collect passenger information on 95% of flights which helps us to identify individuals who pose a threat before they fly."